There are different parameters to assess the quality of PET bottles. Different test can be performed on the sample bottle when preforms are molded into bottles. Some common tests are:
- Wall thickness testing
- Hot wire bottle cutting for measuring sectional weight
- Torque testing
- Base clearance testing
- Top load testing
Irrespective of what is being packed inside, it is important to perform these primary tests to check, if bottles can sustain in harsh real time working conditions. As PET bottles is the commonest form of packaging that is used in industries like pharmaceutical, cosmetics, chemical, toiletries, beverages, colors and paints, etc. You can say that PET is non-reactive material and thus not diffuse any harmful substances into the contents inside. Even if exposed to light, UV, heat; it can act as a strong barrier to air, moisture and water. All these properties of PET have made it a preferable choice for packaging industry
Tips for enhancing the quality of PET bottles
- A PET bottle should be maintaining the balance. When empty of filled with material, the bottle should not topple due to uneven weight distribution. This can be made possible with weighing the sections of bottle. Using a hot wire bottle cutter, the sample is cut into 3 equal sections. According to standards, the weight of each section should be in right proportion. If the neck section has more weight that bottom, it will tend to fall when stand empty. Manufacturer should test the test sample first before starting the mass production.
- When subjected to load higher than prescribed limit, the buckling appears in the bottle. Buckling is the deformation developed due to overloading. Usually, buckling appears at a point where there is a defect, either due to uneven thickness or due to air bubble. If the test material fails to this test, it becomes important to cross check the quality of preforms. Preforms can be tested using polariscope.
- The base of PET bottle has a particular depth, which is important to maintain the balance of the bottle. A device called base clearance meter is used to measure the depth with respect to the diameter of the bottom.
- Uneven thickness of wall may decrease the load bearing capacity and make it prone to bursting when subjected to load, during filling process or during stacking. Magna Mike 8600 is the wall thickness gauge offered by Olympus. Presto is the authorized supplier of Magna Mike 8600 in India. Operator can either cut the bottle into sections using hot wire bottle cutter and then measure the wall thickness. Any inconsistency can be rectified before the starting of mass production.